The field of mid-infrared (IR) detection has grown rapidly in recent years due to increasing demand for a wide range of applications such as gas sensing, thermal imaging, and atmospheric tracking. As the desire for a wider range of applications has grown, the current state of the art, consisting of semiconductor photon detectors and thermal detectors, has been unable to meet all the demands of the growing mid-IR market. Photon detectors offer high sensitivity and speed as well as control over the cut-off wavelength by engineering the band gap of the absorbing material. However, such detectors require expensive, bulky cryogenic cooling to maintain their sensitivity. Additionally, due to the dependence of peak absorption wavelength on the material properties of the semiconductor, fabrication of arrays of detectors configured for different frequencies is expensive and complex.
On the other hand, thermal detectors, of which bolometers are the most popular, can typically operate at room temperature but have been unable to approach the speed and sensitivity of photon detectors. Thermal detectors can be produced and operated for significantly lower costs than cryogenic cooled detectors and consequently have opened up new opportunities in a range of markets, particularly consumer markets. There remains, however, a substantial unfilled vacancy between the two types of detectors for applications where the high cost of photon detectors and the relatively lower performance of thermal detectors make both options unworkable.